Have you tried to stop NBU on the media server and start it again?
Any error messages during startup?

Can you see if the processes are started and then terminate?

I have once seen a similar issue at a customer when a NBU patch was copied to a media server using ssh. We asked the customer to copy the actual downloaded patch (not extracted patch) to the media server and reinstall.
All daemons started up successfully.

PS: Are you aware of the fact that NBU 6.x ran out of support on 3 October?

Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and WindowsHandy NBU Links